Hardfacing process and parts produced thereby

ABSTRACT

A hardfacing process includes depositing a clad layer having a thickness greater than about 1 mm (0.04 in) on a surface of the component by arc welding, and creating a heat affected zone directly below the clad layer due to the depositing. The heat affected zone may be a region of the component where a lowest hardness is more than 40% lower than a base hardness of the component below the heat affected zone. The method may also include heat treating the component after the deposition such that the lowest hardness in the heat affected zone is restored to within about 15% of the base hardness of the component.

TECHNICAL FIELD

The present disclosure relates generally to a hardfacing process andparts produced by the process, and more particularly, to an arc weldinghardfacing process of components subject to mechanical wear.

BACKGROUND

A metal surface that contacts and undergoes relative motion with respectto another surface experiences wear. Wear is the progressive loss ofmaterial from the metal surface as a result of friction between theinteracting surfaces. Excessive wear leads to premature failure of acomponent. Properties such as hardness are important factors thatdetermine the wear resistance of a metal. Hardness relates to theresistance of the metal to scratching or abrasion. The higher thehardness of the metal, the greater its resistance to wear. In somecases, after fabrication of a metal component, a heat treatmentoperation may be performed to increase the hardness of the componentsurface. As a result of the heat treatment operation, a layer ofmaterial at the component surface may have a higher hardness than thebulk of the component. The increased hardness at a surface that willexperience wear improves the wear resistance and prolongs the usefullife of the component. Although in general, surface hardening improveswear resistance, for components that experience very high rates of wear(such as, for example, undercarriage components of a machine, groundengaging tools, TBM wear parts, etc., that are generally referred to aswear components), increased surface hardness produced by a heattreatment operation may be insufficient for a beneficial improvement inwear resistance. Such components may be hardfaced and then heat treatedto further improve its wear resistance.

Hardfacing is a low cost method of depositing wear resistant surfaces onmetal components to extend service life. The American Welding Societydefines hardfacing as “[a] surfacing variation in which surfacingmaterial is deposited to reduce wear.” The term surfacing is defined as“[t]he application by welding . . . of a layer, or layers, of materialto a surface to obtain desired properties or dimensions, as opposed tomaking a joint.” AWS A3.0 Standard Welding Terms and Definitions. Asopposed to a hardening heat treatment operation, which involves changingthe microstructure and mechanical properties of the component surface,hardfacing involves the deposition of a new material on the basematerial of the component. In general, the clad material may have asimilar or a different composition than the base material. Hardfacingmay be performed using a number of well known welding (or cladding)techniques. These known techniques can be broadly classified into threecategories as, arc welding (or arc cladding), thermal spraying, andlaser-based cladding. The current disclosure is specifically directed tohardfacing of a metal component using an arc welding (or arc cladding)process.

There are a number of different arc welding techniques that are commonlyused in the industry to perform hardfacing. These include, for example,gas tungsten arc welding (GTAW), plasma arc welding (PAW), plasmatransferred arc (PTA), gas metal arc welding (GMAW), submerged arcwelding (SAW) and several others. In these processes, an arc isestablished to melt the surface of the base material, usually in thepresence of a shield gas. The clad material, which is introduced ineither wire or powder form, is also melted by the arc to form the cladlayer. Arc welding produces a clad layer that is fully welded andmetallurgically bonded to the substrate of the component. This cladlayer may have a higher hardness, and therefore better wear properties,than the component substrate. However, a major disadvantage of arcwelding is that the high temperatures involved in depositing the cladlayer act to soften (or reduce the hardness of) a layer of material onthe surface of the component beneath the clad layer. This zone ofheat-softened material on the component surface is referred to as theheat affected zone (HAZ). Therefore, although arc welding deposits aclad layer having high wear resistance on the component surface, thewear resistance of the underlying component surface deteriorates as aresult of the heat-intensive welding process. Since the clad layer willeventually wear off after extended operation, reduced wear resistance ofthe underlying component surface detrimentally affects the useable lifeof the component by hastening component wear after the clad layer hasworn off. Also, in some circumstances, a relatively soft under-layer canalso cause the hard clad layer to be crushed or it can crack. Thedamaged clad layer will then spall off the component surface. Inaddition, during the cladding process, the substrate will act like aheat sink and will quench the high hardenability clad layer. This cladlayer will have an as-cast untempered martensite microstructure. Thisuntempered martensite is very hard, but it is also very brittle. Whenthese clad components are subjected to higher impact abrasiveenvironments, the brittle clad layer often chips and spalls.

U.S. Pat. No. 2,249,629 issued to Hopkins (the '629 patent) discloses anarmored article in which an armor metal is produced by fusing together ahard metal with a base metal using electric energy discharge. After thefusing operation, the armored article is subject to heat treatment todevelop the desired hardness in the hard metal and the base metal. The'629 patent disclosed steel chemistry ranges for the base material andheat treatment parameters that would yield base material hardness of 200to 400 Brinell (approximately Rkw C 18 to 43). While the process of the'629 patent includes heat treatment after a welding operation, thisprocess may have deficiencies. For instance, the heat affected zonecreated by the welding process may not be restored by the process of the'629 patent.

The disclosed hardfacing process and products are directed at overcomingthese and/or other shortcomings in existing technology.

SUMMARY

In one aspect, a hardfacing process for a component subject to wear isdisclosed. The process includes depositing a clad layer having athickness greater than about 1 mm (0.04 in) on a steel body of thecomponent having a hardness between about 43 HRC and about 60 HRC usingan arc welding process. The process may also include heat treating thecomponent after the cladding. The heat treating may include austenizingthe component and quenching the component in a liquid bath. The heattreatment may also include tempering the component after removing thecomponent from the liquid bath.

In another aspect, a hardfaced component that is subject to wear isdisclosed. The component may include a steel body and a clad layer whichis greater than about 1 mm thick (0.04 in) metallurgically bonded to asurface of the body using an arc welding process. A lowest hardness ofthe body in an interfacial region that is about six times the thicknessof the clad layer is within about 15% of a hardness of the body belowthe interfacial region.

In yet another aspect, a method of hardfacing a steel component isdisclosed. The method may include depositing a clad layer having athickness greater than about 1 mm (0.04 in) on a surface of thecomponent by arc welding, and creating a heat affected zone directlybelow the clad layer due to the depositing. The heat affected zone maybe a region of the component where a lowest hardness is more than 40%lower than a base hardness of the component below the heat affectedzone. The method may also include heat treating the component after thedeposition such that the lowest hardness in the heat affected zone isrestored to within about 15% of the base hardness of the component.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an illustration of an exemplary undercarriage of a machine;

FIG. 2 is an exemplary track shoe of the undercarriage of FIG. 1;

FIG. 3 is an exemplary grouser of the track shoe of FIG. 2;

FIG. 4 is a schematic illustrating an exemplary process of the currentdisclosure; and

FIG. 5 is a graph plotting the hardness of a track shoe as a function ofdepth from the surface.

DETAILED DESCRIPTION

FIG. 1 illustrates an exemplary undercarriage system 100 of a machine.The components of the undercarriage system 100 help to propel themachine over different types of rugged terrain. During operation of themachine, the components (such as, for example, track shoe 10) of theundercarriage system 100 are subject to especially severe abrasive weardue to the uncontrolled and unlubricated environments that thesecomponents operate in. After extended operation, track shoe 10 wears onsurfaces where the frictional forces acting on them are the highest.With the passage of time, the track shoes 10 wear out and they have tobe repaired or replaced. To extend the useful life of track shoe 10,surfaces of the track shoe 10 that are prone to wear are hardfaced.

FIG. 2 illustrates a exemplary track shoe 10 having a grouser 14. Trackshoe 10 is typically fabricated from a low alloy steel, such as, forexample, low alloy boron steel for enhanced hardenability. As themachine travels on a surface, a top surface 18 of the grouser 14 comesinto contact with, and rubs against, the surface. Therefore, the topsurface 18 experiences severe abrasive wear. For wear protection, thetop surface 18 is hardfaced with a cladding 20. Although FIG. 2illustrates the cladding 20 as being applied only on the top surface 18,this is only exemplary, and in general, any surface of track shoe 10 maybe hardfaced with cladding 20. Furthermore, although cladding 20 isdescribed as being applied to a track shoe, this is only exemplary, andin general cladding 20 may, without limitation, be applied to anycomponent.

Top surface 18 of the grouser 14 of track shoe 10 is hardfaced withcladding 20 using a submerged arc welding process using multipleelectrodes. These multiple electrodes are coupled to one or more arcwelding power sources that work in conjunction to deposit the severalarc welding electrodes into a single molten pool using a commonpotential. During the deposition process, an external flux system isused to stabilize the multiple arcs. This multiple electrode arc weldingtechnology allows for hardfacing grouser 14 using wide clad deposits.The width of the clad deposits may vary based on the number ofelectrodes employed. In general, clad deposits having a width of morethan 5 mm (0.20 in) and a thickness of less than 8 mm (0.31 in) arepossible in a single pass using this technology based on the parametersused in the process (such as, for example, the number of electrodesemployed, traveling velocity, etc.). The ability to deposit wide layersof clad material may increase the efficiency of the cladding process bydecreasing the time (and associated cost) involved in the process.Although a multiple electrode submerged arc welding process was used todeposit cladding 20 on track shoe 10, it is contemplated that any typeof arc cladding process may be used to hardface track shoe 10. Ingeneral, an arc cladding process deposits clad layers at a highdeposition rate (which translates into high throughput) at a relativelylow capital equipment cost, and therefore reduces the overall cost ofthe hardfacing operation. Since a layer of the base material on the topsurface 18 of grouser 14 is also melted during the hardfacing operation,a metallurgical bond is formed at the interface between track shoe 10and cladding 20.

FIG. 3 illustrates a schematic cross-sectional view of grouser 14 (oftrack shoe 10) with cladding 20 thereon. As noted above, track shoe 10is made of a low alloy boron steel. For example, track shoe 10 may beformed of SAE 51B27 steel. However, it is contemplated that track shoe10 may be made of any material that is typically used for suchcomponents. Cladding 20 may also include any material that is used forhardfacing track shoes and other similar components. Several materialsthat are suitable for such purposes are commercially available fromdifferent manufacturers. For instances, materials such as, Lincore® 33,Lincore® 55-G, Lincore® 40-O, Lincore® BU-G, etc. from The LincolnElectric Company and Stoody® 964-G, Stoody® 996-G, Stoody® 130-O,Stoody® Vancar-O, etc. from Stoody Company may be suitable to be used ascladding 20. In FIG. 3, cladding 20 atop grouser 14 is roughly 5 mm (0.2in) thick. In general, the thickness of cladding 20 may depend upon theapplication. However, in general, the thickness of cladding 20 used forhardfacing purposes may be in the order of millimeters (such as, forexample between about 1 mm and 10 mm).

Due to the temperatures involved in the hardfacing operation, aheat-affected zone (HAZ) 16 exists between cladding 20 and the basematerial of track shoe 10. The heat-affected zone (HAZ) 16 is an area ofthe base material that has had its microstructure and properties alteredbecause of the heat-intensive welding operation used to deposit cladding20. The heat from the welding process and subsequent re-cooling causesthis change in the area directly below the cladding 20. The thickness ofHAZ 16, and the property change depends primarily on the chemistry ofthe track shoe 10 material and the amount and concentration of heatinput during the welding process. In one embodiment, the HAZ 16 betweencladding 20 and the base material of track shoe 10 was estimated to bebetween about 20 and 30 mm (0.79 in to 1.18 in). However, in general,the thickness of HAZ 16 may depend upon the materials and the processconditions. For instance, if the thermal diffusivity of the basematerial of the track shoe 10 is high, the cooling rate after weldingwill be high and the thickness of HAZ 16 will be relatively small.Similarly, a low thermal diffusivity leads to slower cooling and athicker HAZ 16. The expected thickness of HAZ 16 during arc cladding anycomposition of steel may be estimated using known mathematical models orby other techniques known in the art. For some embodiments of thecurrent disclosure, the HAZ 16 was estimated to be about 6 times thethickness of the cladding 20.

Regarding the properties of the material in HAZ 16, hardness is aproperty of particular importance in a wear related application. Due tothe heat-intensive welding operation used to deposit cladding 20, thehardness of the material in HAZ 16 will be reduced. In general, thegreater the heat input during the welding operation, the thicker will beHAZ 16. The reduction in hardness in HAZ 16 negatively affects the wearlife of track shoe 10. For instance, because of the hardness reductionin the base material directly below cladding 20, the wear of the trackshoe 10 will proceed at an accelerated pace after cladding 20 has wornoff. Also, in some cases, the presence of a region of soft material(caused due to the reduction of the hardness in HAZ 16) directly belowcladding 20 may cause portions of the overlying cladding 20 to spall offthe surface of track shoe 10. In addition, during the cladding process,the substrate will act like a heat sink and will quench the highhardenability clad layer. This clad layer will have an as-castuntempered martensite microstructure. This untempered martensite is veryhard, but it is also very brittle. When these clad components aresubjected to higher impact abrasive environments, the brittle clad layeroften chips and spalls.

To restore the hardness of track shoe 10 in HAZ 16, the track shoe 10 issubjected to a heat treatment operation after cladding (post-claddingheat treatment). This heat treatment may include austenetizing,quenching, and tempering. During the welding process, in some cases,cracks may form on the surface of cladding 20. Subjecting a hardfacedtrack shoe 10, with cracks in cladding 20, to a temperature excursion(such as, during heat treatment) may induces stresses in the cladding 20that may tend to propagate these cracks into the base material. Thesecracks could lead to premature failure of the component. Therefore theheat treatment conditions of track shoe 10 are tailored to eliminate ordecrease the propensity to propagate any cracks that may be present incladding 20. In some embodiments, the heat treatment process is designedsuch that a temperature change of the track shoe 10 during quench isbelow a temperature change that will cause a crack in cladding 20 topropagate.

Austenizing is a heat treating operation where the actual transformationof the base material (steel) of track shoe 10 takes place. Theaustenizing may include heating track shoe 10 above the austenetizationtemperature of the base material of track shoe 10, and maintaining thetemperature for a desired time. All grades of steel have anaustenetization temperature. The temperature to which track shoe 10 isheated during austenizing depends upon the austenetization temperatureof the steel used to fabricate track shoe 10, and the likelihood ofcrack propagation in cladding 20. In general, this temperature dependson the austenetization temperature of the wear component that is beinghardfaced. For the SAE51B27 steel used in an embodiment of a track shoe10 with cladding 20, austenizing may include placing the track shoe 10in a furnace at a temperature between about 875° C. (1607° F.) and 900°C. (1652° F.) for about 60 minutes. The actual time that track shoe 10is maintained at the austenizing temperature depends on the size andthickness of track shoe 10. In an embodiment, where the thickness oftrack shoe 10 is about 50 mm, the hold time (the amount of time thetrack shoe is maintained at austenizing temperature) is about 60minutes. For thicker track shoes 10, this hold time may be higher. Inpractice, a continuous furnace is used for the austenization of trackshoe 10. In this continuous process, several track shoes 10 arranged ona conveyor are passed through a furnace that includes a zone maintainedat a temperature between about 875° C. (1607° F.) and 900° C. (1652°F.). The track shoes 10 pass through this zone in about 60 minutes.

After austenizing, the track shoes 10 are quenched. Quenching is therelatively rapid cooling of track shoe 10 to a temperature below themartensitic start temperature of the base material (steel) of track shoe10. In an embodiment of track shoe 10, quenching is performed bydropping track shoe 10, which is at the austenizing temperature, into awater bath maintained at a temperature between about 35° C. (95° F.) andabout 41° C. (106° F.). The track shoe 10 is removed from the water bathafter about 40 to 60 seconds. When the track shoe 10 is removed from thewater bath, the track shoe 10 has a residual temperature between about100° C. (212° F.) and about 300° C. (572° F.). In some embodiments, thetrack shoe 10 is removed from the water bath after about 50 seconds whenthe residual temperature of the track shoe is between about 115° C.(239° F.) and about 150° C. (302° F.). In some embodiments, oil or apolymer maintained at a desired temperature may be used in place of thewater bath. The desired temperature of the bath and amount of time thetrack shoe 10 is immersed in the bath depends upon the desired residualtemperature of track shoe 10 after quenching. This residual temperatureis chosen so as to eliminate or reduce the likelihood of any cracks thatmay be present in cladding 20 to propagate. A low residual temperatureincreases the temperature change experienced by the track shoe 10 duringquenching. A larger temperature change increases the stresses that tendto propagate the crack. Similarly, a smaller value of temperature changedecreases the stresses that tend to propagate a crack. Therefore, in anembodiment where the likelihood of cracks in cladding 20 is high, thequenching operation may be tailored to increase the residual temperatureof the track shoe 10. In general, the quenching operation may betailored to reduce the temperature of the track shoe 10 to a temperaturebelow the martensitic start temperature of the steel (of track shoe 10)and above a temperature at which the stresses in cladding 20 will causethe cracks to propagate.

After quenching, martensite is formed in track shoe 10. Althoughmartensite is the desired microstructure for increased wear resistance,the steel is brittle after quenching. Therefore, after quenching, trackshoe 10 is tempered. Tempering is the process of heating the track shoe10 to increase its toughness at the expense of hardness (andbrittleness). In one embodiment, the track shoe 10 is tempered byplacing the track shoe 10 in a tempering furnace maintained at atemperature between about 143.3° C. (290° F.) and about 154° C. (309°F.) for about 85 to about 90 minutes. After tempering, track shoe 10 iscooled to room temperature in air. The track shoe 10 may be allowed tocool in air naturally or may be forced to cool to room temperature at afast rate to save time. It should be emphasized that although heattreatment process conditions for a particular type of steel is describedabove, in general, the process conditions employed during heat treatmentdepends on the type of steel that is hardfaced.

For components that are not hardfaced to improve wear, heat treatment istypically performed after the component is machined or otherwise formed.Heat treatment after forming removes the stresses induced in thecomponent because of the processes used to form the component. Forhardfaced components known in the art, heat treatment is performedbefore hardfacing to prevent the clad layer from cracking. In thecladding process of the current disclosure, a heat treatment process isperformed after the cladding 20 is deposited. This post-cladding heattreatment process may be in lieu of, or in addition to, any heattreatment that is performed after forming track shoe 10. Subjectingtrack shoe 10 to a heat treatment process (that includes austenizing,quenching, and tempering) after depositing cladding 20 may restore thehardness in HAZ 16 to the hardness of the base material, which may, ingeneral be above about 43 Rockwell C (hardness in the Rockwell C scale),or between about 43 HRC and about 60 HRC, in preferred embodiments.Obviously the clad layer also is exposed to the same heat treatmentprocess (that includes austenizing, quenching, and tempering). Tailoringthe conditions of the heat treatment process to eliminate or reduce thelikelihood of crack propagation in the cladding 20 may also improve thequality and reliability of the cladding 20.

INDUSTRIAL APPLICABILITY

The hardfacing process of the current disclosure may be applicable toany application where it is desired to increase the wear resistance ofhardfaced parts. These hardfaced parts produced by the process may beused in any application where increased wear resistance is desirable. Inan exemplary embodiment, a hardfaced part of the current disclosure maybe a track shoe of a machine that is used in a work environment.

The top surface 18 of the grouser 14 of a track shoe 10 (see FIG. 2) washardfaced with a cladding 20 using a multi-electrode submerged arcwelder using an embodiment of the disclosed process. FIG. 4 illustratesa schematic of the applied exemplary process. The track shoe 10 was madeof SAE51B27 low alloy boron steel, and about a 5 mm (0.2 in) thickcladding 20 of Lincore® 55G was applied to the top surface 18 (step200). To evaluate the effect of heat treatment on the HAZ 16 formed dueto the hardfacing process, a track shoe 10 was subject to post-claddingheat treatment (step 400) after hardfacing. The heat treatment processincluded austenizing (step 320), quenching (step 340), and tempering(step 360). Austenizing the track shoe 10 was performed by placing trackshoe 10 in a furnace maintained at about 884° C.±5° C. (1623° F.±41° F.)for about 60 minutes. After about 60 minutes, the track shoe 10 wasdropped in a water bath maintained at about 35° C. to 40° C. (95° F. to105° F.), and removed from the water bath after about 59 seconds. Theresidual temperature of the quenched track shoe 10 was between about115° C. (239° F.) and about 150° C. (302° F.). Tempering was performedby placing the quenched track shoe 10 in a tempering furnace maintainedat about 149° C. (300° F.) for about 87 minutes. After this time, thetrack shoe 10 was cooled to room temperature in air.

The hardness of the track shoe 10 from the surface of cladding 20 as afunction of depth into the cladding 20 (and grouser 14) was thenmeasured. To evaluate the impact of the post-cladding heat treatment onHAZ 16, hardness tests were also performed on a similarly hardfacedtrack shoe which was not subjected to post-cladding heat treatment(control sample). FIG. 5 is a curve comparing the observed hardness as afunction of depth into the grouser 14 for the track shoes with andwithout post-cladding heat treatment. Since the thickness of cladding 20on track shoe 10 is about 5 mm (0.2 in), the measured hardness for thefirst 5 mm (0.2 in) (region marked “a” in FIG. 5) represents thehardness of the cladding 20. As evident from FIG. 5, the hardness of thecladding 20 of the control sample is about 5 HRC higher than thecladding 20 of the track shoe 10 which was subject to post-cladding heattreatment. This observed reduction in surface hardness is due totempering of the cladding 20 of the heat treated track shoe 10. Duringtempering, toughness of cladding 20 increases at the expense ofhardness. The region marked “b” below the cladding 20 (from about 5 mm(0.2 in) to about 32 mm (1.26 in) from the grouser surface) is theheat-affected zone (HAZ 16). Comparison of the curves in this regionshows a substantial reduction in hardness of the control sample.Analysis of the data indicates that, in the control sample, the lowesthardness in HAZ 16 was about 57% lower than that in the bulk material(marked “c” in FIG. 5). This reduction in hardness is the effect of theheat-intensive welding operation used to deposit cladding 20. Theobserved trend of the hardness in this region is as a result of thedifferent temperatures that different regions of HAZ 16 (below thesurface) experience as a result of the welding operation, and thediffering amounts of hardness that result therefrom. In the heat treatedtrack shoe 10, however, the subsequent post-cladding heat treatmentrestored the hardness in HAZ 16 to a value substantially equal to thehardness of the bulk material. At depths greater than about 32 mm (1.26in) (marked “c” in FIG. 5), the hardness of both the samples are equalto the hardness of the bulk material (about 47 HRC). Analysis of thedata indicated that, in the heat treated track shoe 10, thepost-cladding heat treatment restored the hardness in HAZ 16 to within10% of the hardness of the bulk material. As evident from FIG. 5,post-cladding heat treatment significantly improves the hardness of ahardfaced track shoe 10 in HAZ 16. Although the surface hardness of thecladding decreases slightly after post-cladding heat treatment, it isbelieved that the increase in hardness of the HAZ region far outweighsthis slight decrease in surface hardness. Also the clad layer is muchtougher after heat treatment and it will resist chipping and spalling.

To evaluate the impact of different processing parameters (such as, forexample, different track shoe materials, cladding materials, claddingconditions, etc.) on the hardness in HAZ 16, multiple track shoes (thatwere heat treated prior to cladding) were clad using the differentprocessing conditions. The hardness of these samples, which were notsubject to post-cladding heat treatment, were measured as a function ofdepth into the grouser of the track shoe. It was observed that thelowest hardness measured in the HAZ of these track shoes were betweenabout 40% and 95% below the bulk hardness of the track shoe material. Tostudy the effect of post-cladding heat treatment, track shoes hardfacedusing the same processing conditions were subjected to differentpost-cladding heat treatment operations (with different pre-heats,austenizing and tempering temperatures, hold time, quench media, etc.).The hardness of these hardfaced track shoes, that were subject topost-cladding heat treatment, were then measured as a function of depth.It was observed that, although, the absolute value of measured hardnessin each case was a function of the particulars of the heat treatmentoperation, in all cases, post-cladding heat treatment restored thehardness in the heat-affected zone to a value substantially equal tothat in the bulk material. While in some cases, the hardness in HAZ 16was restored to within about 5% of the hardness of the bulk material, inall cases, the hardness in HAZ 16 was restored to about 15% of thehardness of the bulk material.

By heat treating a hardfaced steel component after the claddingoperation, the hardness of heat affected zone, caused as a result of theheat-intensive hardfacing operation, may be restored to a valuesubstantially equal to the hardness of the base material. In general,after the heat treatment, the hardness of the heat affected zone may berestored to within 15% of the hardness of the base material, while insome cases, the hardness may be restored to within 10%, or even 5% ofthe hardness of the base material. The heat treatment may also betailored to prevent the propagation of any cracks that may be present inthe cladding before the heat treatment.

It will be apparent to those skilled in the art that variousmodifications and variations can be made to the disclosed hardfacingprocess. Other embodiments will be apparent to those skilled in the artfrom consideration of the specification and practice of the disclosedcladding process. It is intended that the specification and examples beconsidered as exemplary only, with a true scope being indicated by thefollowing claims and their equivalents.

1.-9. (canceled)
 10. A hardfaced component that is subject to wear,comprising: a steel body; and a clad layer, greater than about 1 mmthick (0.04 in), metallurgically bonded on a surface of the steel bodyusing an arc welding process, wherein a lowest hardness of the steelbody in an interfacial region that is about six times the thickness ofthe clad layer is within about 15% of a hardness of the body below theinterfacial region.
 11. The component of claim 10, wherein the componentincludes a wear component having a hardness between about 43 HRC andabout 60 HRC.
 12. The component of claim 10, wherein the clad layer ismore than about 5 mm (0.2 in) thick.
 13. The component of claim 10,wherein the steel body includes SAE 51B27 steel. 14.-20. (canceled) 21.A hardfaced component that is subject to wear, comprising: a steel body;a clad layer, greater than about 1 mm thick (0.04 in), metallurgicallybonded on a surface of the steel body using an arc welding process,wherein a lowest hardness of the steel body in an interfacial regionthat is about six times the thickness of the clad layer is within about15% of a hardness of the body below the interfacial region; and a heataffected zone directly below the clad layer, the heat affected zonebeing a region of the steel body where a lowest hardness is more than40% lower than a base hardness of the steel below the heat affected zonebefore heat treating and where a lowest hardness is about 15% of thebase hardness after heat treating.
 22. The component of claim 21,wherein the component includes a wear component having a hardnessbetween about 43 HRC and about 60 HRC.
 23. The component of claim 21,wherein the clad layer is more than about 5 mm (0.2 in) thick.
 24. Thecomponent of claim 21, wherein the steel body includes SAE 51B27 steel.25. The component of claim 10 further comprising a heat affected zonedirectly below the clad layer, the heat affected zone being a region ofthe steel body where a lowest hardness is more than 40% lower than abase hardness of the steel below the heat affected zone.
 26. Thecomponent of claim 10 further comprising a heat affected zone directlybelow the clad layer, the heat affected zone being a region of the steelbody where a lowest hardness is about 15% lower than a base hardness ofthe steel below the heat affected zone.
 27. The component of claim 26,wherein the component includes a wear component having a hardnessbetween about 43 HRC and about 60 HRC.
 28. The component of claim 26,wherein the clad layer is more than about 5 mm (0.2 in) thick.
 29. Thecomponent of claim 26, wherein the steel body includes SAE 51B27 steel.30. A hardfaced component that is subject to wear, comprising: a steelbody; a clad layer, greater than about 1 mm thick (0.04 in),metallurgically bonded on a surface of the steel body using an arcwelding process, wherein a lowest hardness of the steel body in aninterfacial region that is about six times the thickness of the cladlayer is within about 15% of a hardness of the body below theinterfacial region; and a heat affected zone directly below the cladlayer, the heat affected zone being a region of the steel body where alowest hardness is between about 15% and 40% lower than a base hardnessof the steel below the heat affected zone.
 31. The component of claim30, wherein the component includes a wear component having a hardnessbetween about 43 HRC and about 60 HRC.
 32. The component of claim 30,wherein the clad layer is more than about 5 mm (0.2 in) thick.
 33. Thecomponent of claim 30, wherein the steel body includes SAE 51B27 steel.